Apparatus for magnetic flocculation of agglomerates



United States Patent [111 3,536,198

[72] Inventors Jeny Ammnikand .2,607,492 8/1952 Anders 210/222 Alfredo F.SanMiguel, Erie, Pennsylvania 2,954,122 9/1960 Colbum 209/214 [21] AppLNo. 765,275 3,142,638 7/1964 Blalsdelletal 210/53 S d :320 Primary Examiner-Michael Rogers atente Anorne Charles L. Lovercheck [73] Assignee Erie: Manufacturing Company y Erie, Pennsylvania in corporation of Pennsylvania [54] APPARATUS FOR MAGNETIC FLOCCULATION ABSTRACT: The process and apparatus of removing fine suspended agglomerates containing existing or added fer- OF AGGLOMERATES 1 Claim, 4 Drawing Fias romagnetlc particles from liquids by the combination of magnetic flocculation and chemical flocculation. These fine [52] US. Cl 2] 0/223 Suspended agglomerates are f d by adding Suitable chemi Int."

Bold 21/01 cal flocculants to the liquid. The effluent will then flow ol'Search through a suitable magne'jc to magnetize the ag- 5154222v223;209/2l4 glomerates. These magnetically induced agglomerates will then attract each other and form large agglomerates which {56] References Cited will settle in a suitable basin. The magnetic apparatus dis- UNlTED STATES PATENTS closed herewith could be added to existing chemcial flocculal,705,869 3/1929 Lewis 210/223 tion systems Patented Oct.'27, 1970 Sheet 2 013 v N N INVENTOR. JE zY A. BARTNIK ALFREDO F SANMIGUEL BY 1 Pat ented Oct. 27, 1970' Sheet 2 SETTLING RATE (INCHES) Scrnme TIME (Mmurss) INVENTOR. XERZY A. BARTNIK v LFREDo ESAN MIGUEL Patented Oct. 27, 1970 Sheet INVENTOR v JEFZYZY A..BARTNIK ATTORNEY ALFREDO F SANMIGuEL BY APPARATUS FOR MAGNETIC FLOCCULATION OF AGGLOMERATES FIELD OF INVENTION This invention relates to the separation of solids from liquids and, more particularly, to the removal of fine suspended solids from liquids by the combination of chemical flocculation and magnetic attraction.

DESCRIPTION OF PRIOR ART OBJECTS or THE lNVENTlON It is an object of the invention to provide an improved method of removing solids from liquids by the combination of the addition of flocculating chemicals, magnetization of the flocculated particles, and settling of the flocculated material, wherein the addition of flocculating chemicals is reduced.

Another object of the invention is to provide a method of carrying out a chemical magnetization process wherein the size and cost of settling basins ever known processes may be reduced.

Another object is to apply the magnetic flocculation process to chemical flocculation effluents containing nonmagnetic solids.

With the above and other objects in view, the invention comprises the processes set forth in the specification, drawings, and recited in the appended claims. The invention will be better understood from a reference to the drawings and detailed specification wherein:

FIG. 1 is an outline view of an apparatus for carrying out the invention;

FIG. 2 is an enlarged view of one component of the apparatus;

FIG. 3 is a graph showing the relation of the process disclosed herein; and

FIG. 4 is a diagrammatic view of the feeding mechanism of the invention.

Flocculation is the process of coagulation or coalescense of finely divided particles, is commonly used in separating fine solids from liquids. It increases the solids settling rate, filtering rate and clarity of the supernatant liquid.

Floccule consists largely of finely divided solids loosely clustered in an aggregate predominantly aqueous, perhaps miscellar in form.

Forces disposing the particles to flocculate include magnetism, ionic forces of attraction and secondary entropic.

forces. Each particle has an unmeasurable but considerable surface tension. Reduction of the particles surface tension can be achieved by adherence to other particles, provided the surfaces are unionized with alike charge. Therefore, the best flocculation occurs at iso-electric point and accords with the second law of thermodynamics.

CHEMICAL MAGNETIC F LOCCULATION unlike pole of the magnetized agglomerates will result in attraction and formation of large agglomerates with sufficient mass to settle rapidly in a suitable basin or thickener.

The chemical flocculants used in theprocess are polyelectrolytes of high molecular weight, water soluble, synthetic polymers, pH regulators and starches. They are usually added as solution in concentration of about 1 percent. Normal addition of chemical flocculants is betweenilo and 10 parts per million, but using the process disclosed, the normal dosage of flocculant can be reduced by about 50, percent. In addition, the results so far conducted indicate that the settling rate after chemical-magnetic flocculation was more rapid than after chemical flocculation only.

Magnetic flocculators used for this application should have a fieldstrength of approximately 800 gauss in the center line between the poles and allow a minimum residence time of the liquid in the magnetic area of one-twentieth of a second Although, in some applications, higher fields and longer time of residence was required for the satisfactory flocculation.

DETAILED DESCRIPTION The chemical magnetic flocculation system will consist of:

l. A volumatic feeder 40 for feeding the dry chemical flocculant.

2. A mixing tank 42 with a vibratory stirrer and water supply 38'to dissolve the chemical reagent. 1

3. A flow meter to control the flocculating reagents feed rate. 4. A pipeline 14 to feed the reagents.

about 10 feet in front of the flocculating magnet.

6. Stainless pipe section 15 around which flocculating magnets 17-19 are located.

magnet and, where possible, further than this.

or circular.

5 5 flocculatIon process.

APPLICATION OF THE PROCESS DISCLOSED The chemical-magnetic flocculation process can be used to agglomerate the majority of the fine solid from liquids, as in the following examples:

I. Blast furnace dust. 2. Flyash dust. 3. B.O.F. dust. 4. Bessemer furnace dust. 5. Open hearth furnace dust. 6. Electric furnace dust. 7. Cupola dust. 8. Fine mill scale. 9. Machining and cutting lubricants. 10. Total steel plant effluent. l 1. Red mud from Bayer Process (aluminum).

cles, like B.O.F. dust, which will carry the magnetic charge.

5. A liquid injector 39 to spray the reagent in the pipeline with influent to be clarified. This should be performed In operation, the volumatic feeder 40 will uniformly feed the dry chemical reagent 41 into the mixing tank. A water flow valve controls the addition of water into the mixer tank to l percent concentration. This also regulates the amount of reagents added to the effluent to be clarified. Normally, by a plastic pipeline and spray nozzle, this solution is fed into the pipeline 13 carrying the effluent to be flocculated. This inlet should not be closer than 10 feet away from the flocculating After the correct amount of reagent has been added to the slurry and fine flocculation occurs, the agglomerates pass through the flocculator magnet and become magnetically charged. The magnetic flocculator should be placed as close as possible to the discharge point and around a stainless steel nonmagnetic pipeline 15. This pipeline could be rectangular The flocculating and settling characteristics of nonmagnetic effluents is enhanced by addition of fine ferromagnetic parti- TYPES OF CHEMICAL FLOCCULATlNG REAGENTS The probability of particle adhesion can usually be increased by the addition 'of one orseveral reagents known as flocculants. These reagentsact as flocculants through one or a combination of three possible mechanisms: g

. l..lt is generally heldthat-when solids are'suspended in a 1, liquid, a double-layerfof ions exists atthe surface of the solid particles. The electrostatic nature'of this double layer is such that like solid particlesare repelled by each other due to like 10 surface charges known as Zeta potential. The first class of flocculants, called electrolytes, acts by neutralizing this intermolecular repulsive force. This, permits natural attractive forces, known asVande' Waals cohesive force, to causethe 1 particles to adhere. This electrolytic neutralization of the Zeta l 5 potential also makes the solids more amenable to further ad- 7 hesion by. one of the two other types of flocculants'.

2. The second class of flocculants, called coagulants, consists of reagents that cause the precipitation, withina definite 1 chemical effects. g

3. The third class of flocculants, called polyelectrolytes,

' consists of either natural .or syntheticlong chainhigh molecug lar weight organic polymers that have a large number of active 1 sites'alongtheir chain length. These polymers Iformga bridge Electrolytes (pH regulators) q Coagnlants Polyelectrolytes Sodium hydroxide, sulphuric Alum Polymer c! polyacid. acrylumidc. Calcium hydroxide Lime .Ifolypger of acryl arm e.- Potnssium hydroxide ammonia-.. (prefer pH of 7). Polymleroit oly- 45:

acry am 2. Calcium carbonate hydrochloric Guar gum.

ac Nitric Acid j .1

TEST RESULTS The test results indicate that the settling rate in chemicallymagnetic flocculation process is doubled over the chemical flocculation only. At thesame time; to attain this, about 50 percent of the chemical reagent is used. Clarity of the super: l

natants from the chemically-magnetic flocculated effluents in most cases ismuch clearer (less than 20 parts per million of solids); Y v n Now with more particular reference to the. drawings, the device shown in FIGS. 1 and 2 has a tank 10 where the liquid with entrained flocculated material is deliveredand where the entrained liquid settles. The tank l0'has distributor 2l.at approximately its center so that the materialflows from the dis- 5 tributor in all directions into the tank. The tank has a sludge outlet 11 and an outlet for clean water for recirculation at 12; at the top of the tank. A conduit l3'connects asuppiy of liquid 1 having the. entrainedparticles therein and the flocculating chemical material is added'atl4 and passes with the liquid 70 through the elbow.l6 to the magnetunit l5. The magnetunit- 15 is flattenedout adjacent the magnets 18 and 19 so that the passage between the magnetelements l8 and 19. is a relatively short distance comparedto the diameter oftheconduitilli. Y

Valve 2l is provided in line 20 with handwheel 22 adjacent 2. 3. ercent of Sollds=0.28. t 4. Percent of Magnetic Iron in Solids=17.4.

pH range, of voluminous metallic hydroxide flocs. These large gellikel flocsphysically entrap the fine particles in the suspension andlsweep them down as they settle quite apart from any 4 catwalk 23. The magnet unithas the flanges land 25 by which the magnet unit can beattached to theconduit l3 and V the liquid passes between the flattened emu between the magnets. g The apparatus may be used to removefinely entrained particles, such as, for example, fly ash, blast furnace. dust and other materials. The materialsthatmay be used'are shown in t the following example:

EXAMPLE A blastfurnace dust slurry was made by adding blast furnace dust of the following size .towater in the following weight percentage of dust to water: l I I 1. Structure: 1

Microns +45 45+30 30+20 -'-20+10 -10 fiergegt weight 12. 81 11. 58 17. 42 28. 49 29.

To determine the efficiency of the flocculation process, the following investigation was conducted: 1

The tests were performed on L000 ml. representative samplesplaced into 1,000 ml. measuring cylinders. In order to flocculate the solids, a predetermined amount of the chemical reagent was added and mixedgentlywith the slurry for 10 seconds. The settling and clarifying rates of the solids were then recorded. When the solids settled, half of thesupematant liquid from the measuringcylinder was'syphoned off 'and solids content in PPM determined.

Next, the same flocculation tests were conducted with 1 percent and 50 percent of the original quantity of the chemical flocculating reagent anddeterminedsolids settling rate and solids content in the supernatant liquid.

Similartests were conducted with the identical addition of I chemical flocculating reagents, but after mixing the slurry in the measuringcylinderswas magnetized'for one-tenth second at 1,000 gauss.

The results as shown on the attached chart, table 1, proved that the chemical-magnetic flocculation process is superior to the chemical flocculation process, requires less reagents and results in cleaner water. 3

All of the tests were conducted in duplicateand the agreement between the results was close.

TABLE I Reagents Settlpeg Cgalritg,

Type olflocc. Description. P.p.n1. ftJhr. solids 1 iso+20 1) 4.0 (1 82 also. plus Chem 2) a1+1s 2 3.1 2 91 Alum a 25+10 is; 1.0 is 93 I 1550- -20 1 6.0 1)62 flgJcheltl- 1,000gauss "d g gg g :1: I 1 1.0 (1) 41s 51 51 Chem Jaguar 0-10--. 2; 0. 75 2) 4.1 2) as 3 0.50 a $379 y 1 1.0 g1 5.x 1 a1 Mag./chem., 1,000 gauss do ztggg (g (8) a) I 1 10 t1 5Z0 1 s4 Chem. Separan AP30.. 3. 7 3 g) 3.3 g a? 1 1 in 13,019 1 as Mag./cl1em.;1,000gauss -.do .2 (g 1) 10 15510 51 as one We (a; as s s I 1 1.0 $17.2 hi as Mag./chem,, 1,000 gauss ..do 1G2!) g) (1 '1.0 1; 5.0 1 a2 Chemmucus-012.-- tzgggg 3 it; 33g .h d 093 -72 a as 1 i8 M 1,000 o V r a 0.110 a 7.8 a 12 BBER TABLE II.TEST RESULTS-MAGNEIIZING OHEMICALLY FLOCCULATED SORU SLIMEB Flyash-Structure Percent Microns Weight weight Couunma-Magnatic flocculation greatly increases the rate .of settling and clarity of the supernatant.

We claim:

TABLEI V.TYPICAL FLOCCULATION E XAHPLE S BasicO en Natural Msgnstlte; Furnace ust Oh ica l l z 'cheml emn ca Typeotllocculstion cs1 1,000 3. .esl I 1,0005.

Percentsolids 1.0" 0.5 0.5 Particle --s2s+s -20 --2o 40 Temperaturs, 20 20 20 11.--; 8.0 as 8.5

hemlcal flocculstorn )v P. .m.olchsm1csl flooc +20 10+10 1.0 1.0 30 3,315. L2 as an 1 so a oi um) -11---. 4o so so 15 I HsSOs plusAlum.

IsguarC-IO.

The foregoing specification sets forth the invention-m its 1 preferred practical forms but the process disclosed is capable of modification within a range of equivalents without departw ing from the invention which is tobe understood is broadly novel as is commensurate with the appended claims. 2 5

1 An apparatus for removing nonmagnetic suspended solids from a liquid containingmagnetic particles comprising:

a relatively large settling tank; a

means at the bottom of saidtanlt tore move sludge from said tank; I a means adjacentthe top of said tank to remove clear liquid; a conduit connected to the top of said tank for supplying liquid containing suspended solids; addition means to add a chemical flocculant to said liquid in said conduit;

amagnet unit disposedbetween; said addition means and said tank for magnetizing said particles; said magnet unit comprising: magnetic means disposed on opposite sides of said conduit "whereby a magnetic field passes through said conduit and through said liquid; whereby said particles are magnetized; a a a magnet conduit section having a flow passage substantially lesser in dimension in the direction said magnetic field passes throughsaid conduit at said magnet unit than in g the direction at right angles thereto; and

said magnet cross section being made of nonmagnetic material and said magnet has one pole on one side of said conduit and another pole on theother side. 

